Prefabricated glass fiber rivet body



All@ 10 1954 J. A.v| AMPMAN ET AL l 2,685,813

PREFABRICATED GLASS FIBER RIVET BODY Filed Sept.v 18, 1951 v -I '1...'. d..." I- .i

mummy/ Patented Aug. 10, 1954 NT oFElcE l PREFABRICATED GLASS FIBER RIvE'r BODY James A. Lampman, Inglewood, and Harold E.

Remillard, Anaheim, Calif., assignors to Northrop Aircraft, Inc., Hawthorne, Calif., a corporation of California Application September 18, 1951, Serial No. 247,172

ll Our present invention relates to glass fiber rivets and more particularly to improvements of the invention described, shown, and claimed in our copending application Serial No. 233,368, filed June 25, 1951, and now abandoned, wherein we teach a means and method of riveting material such as plastic impregnated glassfabric sheets together with plasticized glass ber rivets. In this manner radomes, for example, can be fabricated of such materials, with riveted joints therein so that the transmission of radio or radar frequency waves through the radome wall is substantially uniform throughout. It is one of the objects of our present inven tion to provide a glass fiber rivet body which can be mass produced, packaged, and stored if necessary, for future use.

Another object of our invention is to providey a glass fiber rivet body of uniform diameter and smooth contour, which is easily inserted into bores of somewhat the same diameter without having unraveled strands of the glass ber catching or piling up at the bore openings when being inserted therein.

Briefly, our present invention, in one preferred form, comprises a plurality of plasticized glass ber threads of uniform length, grouped together to form a generally cylindrical bundle body of uniform diameter, and incased from one end to the other in a tight sleeve of a thermoplastic material for example, the rivet body being 4 Claims. l (Cl. 87-1) adapted to be upset by heat and pressure to proy vide a solid headed rivet.

This invention will be more easily understood by referring to the drawings wherein:

Figure 1 is a diagrammatic view in longitudinal section, showing a bundle of glass ber threads being inserted into a plastic sleeve, using the pressure of an air blast to distend the sleeve.

Figure 2 is a diagrammatic View in longitudinal section in which the glass fiber threads have been extended through the length of the sleeve, and the air blast discontinued.

Figure 3 is a side elevational view of a length of rivet body; the sleeve being cut away to show the incased glass liber threads.

Figure 4 is a side elevational View, partly sectionalized to show the rivet body of Figure 3 out to size and inserted in the aligned bores of a pair of plastic sheets to be riveted.

Figure 5 isa side elevational View, partly sectionalized to show the rivet being upset and cured in the aligned bores of Figure 4.

Figure 6 is a side elevational view, partly sectionalized to show the completed rivet.

Figure '7 is a side elevational'view of the present invention'in another form wherein the sleevev is of a loosely braided construction.

Figure 8 is a side elevational View of the sleeve of Figure 7 tightened around the glass fiber threads.

Referring first to Figure l, a number of glass fiber threads I0, of approximately the same length; are grouped together into a generally cylindrical'elongated body II with the threads I 0 running lengthwise along the axis thereof. The body I I is impregnated with a wet, i. e., partially cured plastic to hold the threads in place. In most cases it will be desirable to twist the body I I so that the threads II) spiral along the axis thereof, as in a cable for example. In one preferred method of encasing the body I I as shown in Figures 1, 2, and 3, the body II of glass ber threads I0 is fed into one end of a rigid tube I2 having a slightly greater diameter than the body I I. At the other end of the rigid tube I2, a thin walled sleeve I4 of a thermoplastic material, such as found in the vinyl or acetate groups, for example, and preferably cured, has one end thereof stretched over the opening of the rigid tube I2. The inside diameter of the plastic sleeve I4 should be slightly less than the outside diameter of the body II of glass fiber threads I Il in the twisted form as mentioned above. A blast of compressed air or gas A is then applied around the bundle II at the feed end of the rigid tube I2 as shown, to distend the plastic tube I4 while the body II 0f glass ber threads is extended therethrough. When the plastic tube I4 is lled, from one end to the other, or to any given length, with the glass iibers I0, the air blast A is discontinued, as shown in Figure 2, and the plastic sleeve I4 exerts force in returning toward its original diameter, which was slightly smaller than the diameter of the body II of twisted glass bers I0, and tightly incases the glass fiber body II therein. Rivets I5 of any desired length can then be out as shown in Figure 3.

It can thus be seen that the finished glass liber rivet body I5 has a uniform diameter and smooth surface and can be inserted into the aligned countersunk bores I6 of a pair of plastic sheets Il to be fastened together, as shown in Figures 4, 5 and 6 wherein the rivet body l5 is subsequently subjected to heat and pressure, to laterally crush outwardly the ends of the glass fiber threads ID to form the heads I9 in the countersunk portions 20 of the bores IE, and cured. The heads I9 of the rivet I5 are then made ush with the surfaces of the sheets l1 and a high shear strength joint of electrical uniformity is thus formed.

In Figure 7, another form of casing for the glass fiber threads is shown, wherein a sleeve 2l is loosely braided from strips 22 of cured thermoplastic material or impregnated glass fiber. The sleeve: 2l is purposely retained in the loosely braided form so that the diameter will accommodate easy extension of the grouped glass ber threads i therethrough. The ends of the sleeve 2l are then pulled strongly in oppositetdirections which evenly tightens the braided sleeve 2| around the glass fibers I9 Ias shownin Figure 8. The rivet body thus formed can then be `saturated With uncured plastic binder and partially set to prevent the Woven sleeve from unraveling at the ends.

It is at once apparent from the foregoing 'description, that there is provided a glass viiber rivet body which can be uniformly made kin standard diameters, having a smooth surface for easy insertion into bores, and which can be mass produced and stored for future use.

While in order to comply with the statute, the invention has been described in language more or less specic as to structural features, it is to be understood that the invention is not limited to the specific features shown, but that the means and construction herein disclosed comprise the preferred form of putting the invention into effect, and the invention is therefore ,claimed in any of its forms or modication Within the legitimate and Valid scope of the appended claims.

What isclaimed is:

1. A prefabricated glass ber rivet body of uniform diameter and smooth surface, comprising 4 a plurality of glass fiber threads grouped together to extend longitudinally, in an elongated body, and said body being impregnated with a partially cured plastic binder, and a thermoplastic sleeve, said glass ber threads being extended through said sleeve and tightly pressed together by =said sleeve, said vrivet blody being adapted to be upset by heat and pressure to provide a solid headed rivet.

v2. A prefabricated glass fiber rivet body of uniform diameter and smooth surface, comprising a plurality of glass ber threads longitudinally twisted around Aeach other to form a cylinimpregnated with partially cured `plastic to hold said strips tightly around said fiber threads.

4. A rivet body in accordance with claim 1 wherein said sleeve is braided of glass fiber yarn.

References -Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,184,899 Shand Dec. 26, 1939 2,284,728 Dreyfus June 2, 1942 2,311,704 Simison Feb. 23, '1943 2,327,104 Gudebrod Aug. 17, 1943 2,344,181 Stone Mar. 14, 1944 `2,500,332 Whitehead Mar. 14, 1950 

